The extragalactic universe is abundant with sources that are associated with the most powerful persistent phenomenon in the universe: accreting supermassive black holes that form Active Galactic Nuclei (AGN). Numerous AGN launch relativistic twin jets of plasma from the immediate vicinity of their black holes which, when oriented close to the line of sight to the observer, give rise to a class of AGN named blazars.

Observations by the Fermi satellite and ground based imaging Cerenkov telescopes show that many blazars are prodigious sources of gamma-rays at tera-electronvolt (TeV) energies. Their impact on the energetics of the universe, however, has previously been thought to be slim since their luminous output is a minor component of the total radiative power in the universe. However, recent work by the PI and his collaborators suggest that TeV blazars are, in fact, remarkable sources of energy. By studying pair beams (electron-positron pairs that are produced when photons from TeV blazars meet extragalactic background light photons) the PI argues that blazars are the dominant heat source in the intergalactic medium (IGM) at redshifts 2-3. This would have substantial implications for the evolution of the universe.

The PI will perform a detailed analysis of the cosmological implications of TeV blazars, which will touch on many different areas of astrophysics: from linear plasma instabilties, to weak turbulence and thermalization, to thermodynamics of the IGM, and to the formation of galaxies and clusters. He will (1) investigate the plasma physics of ultrarelativistic pair beams, (2) set blazar heating in a cosmological context, and (3) explore the implications of his work for the structure formation of the universe.

The PI will disseminate his research to a broad audience in numerous ways. First, he will reimagine introductory physics classes at the University of Wisconsin-Milwaukee (UWM), by combining traditional lectures with online video lessons and exercises. He will also work closely with the Astronomy Club at UWM by recruiting undergraduates and high school teachers for semester and summer research projects. Finally, the PI will perform public outreach by producing and giving public lectures through the Astrobreak series at the nearby Manfred Olson planetarium.

National Science Foundation (NSF)
Division of Astronomical Sciences (AST)
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James Neff
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University of Wisconsin Milwaukee
United States
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